Republican candidates mocked President Barack Obama during the Thursday night debate in Iowa over his handling of the downed U.S. drone in Iran.

"This is a president that the spy drone being brought down, he says pretty please? Foreign policy based on pretty please? You have to be kidding," former Massachusetts Gov. Mitt Romney said. "This is a president who fundamentally believes that the next century is the post-American century. Perhaps it will be the Chinese century. He is wrong. It has to be the American century. America has to lead the free world."

On Monday President Obama acknowledged Iran had the drone in its possession. "We've asked for it back," he said. "We'll see how the Iranians respond."

Texas Gov. Rick Perry also chastised Obama, saying the U.S. should have either destroyed the craft or obtained it so that sensitive technology wouldn’t fall into Iranian hands. Perry called Obama’s reaction to the felled drone "the worst and the weakest."

The drone—a bat-winged RQ-170 Sentinel—was on a CIA mission when it went missing on Dec. 4, according to US officials. Meanwhile Iran has promised it would "reverse-engineer" the craft to exploit its technology.

Iran was the hot foreign policy issue during the Iowa debate Thursday. Michele Bachmann and Ron Paul sparred over Iranian nuclear ambitions, with Texas Rep. Ron Paul suggesting there is no evidence of Iranian nuclear weapons.

Paul called Minnesota Rep. Michele Bachmann's suggestions that Iran is bent on destruction of the U.S. and its allies, including Israel, "absurd" and "dangerous talk." The Libertarian-leaning candidate also said terrorists aim to harm the U.S. because it invades their countries.

Bachmann responded that she had "never heard a more dangerous" talk than Paul’s suggestion that the U.S. work with Iran to put an end to nuclear ambitions, arguing Iran puts American lives at risk and aims to "wipe our ally Israel off the face of the map."

The exchange comes after the U.S. House of Representatives' passed additional sanctions against Iran.

Paul, a critic of wars in the Middle East, is the only GOP candidate who believes military action or intervention in Iran would be counterproductive.

Former Utah Gov. Jon Huntsman and former Speaker of the House Newt Gingrich squared off on Monday at St. Anselm College in New Hampshire. Both presidential contenders agreed that Iran is the number one threat to stability in the Middle East.

"Iran is the transcendent issue of this decade," said Huntsman, arguing that Iranian uprisings in 2009 presented a huge opportunity to impact regime change in Iran that the U.S. missed. "We go to Libya, where arguably we have no real defined national security interests, we scratch our heads over Syria, and we lecture Israel all the while."